Thursday 18 June 2020

Carl Martin Plexi Tone 9v/-9v


7 comments:

  1. Oh sweeet heavenly jeebus xx

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  2. Theres a problem with the boost section but crunch and hi gain sound good.
    Would increasing the 68nf cap increase the treble?

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    Replies
    1. The boost sounds harsh and unboost like and it feels like its after the main drive? I dont know. Tbh, ive jumpered both the board boost holes and left it off.

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    2. I'll take another look at boost section tomorrow. Which op amp do you use?

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    3. I've been over the schematic again and I can't spot any errors. Boost control essentially is a gain control at the last gain stage....
      http://4.bp.blogspot.com/-ier5Qk_vR-U/Tx1MsJ0sKoI/AAAAAAAAAro/1KKJZX2vyy4/s1600/Plexitone_rev3.gif

      If you want more treble from the tone control I think you need to reduce 68nF cap.

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    4. Found another schematic that has Boost switch lugs 2 and 3 tied together. Worth trying out?
      https://s272.photobucket.com/user/harrisxr650/media/marshall%20preamp.jpg.html

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  3. Hmm. I always thought it was at the beginnening. I increased the pot to 10k, added a substantial amount and i was thinking of playing with the cap. Im gonna definatly do a dual footswitch version. I cant decided between this and the jhs @ at the moment. Marshally goodness.

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